This invention is an off-line switching power supply for generating negative voltages. More specifically, this invention is an off-line switching power supply for generating negative voltages so that a transformer is not required.
Switching power supplies are widely used in a number of applications. They are often preferred because they are very efficient in that there is very little power dissipation by a transistor switch that switches between being off and being saturated. Despite this and other advantages of switching power supplies, problems remain.
One problem is generating negative voltages such as for the control of triac driven AC loads. In order to generate negative voltages, a flyback transformer is used. The flyback transformer is used to provide for inverting of an input voltage. The addition of a flyback transformer adds substantial cost to the power supply. In addition, transformers can be large in size, thus require increased space and further increases in manufacturing costs. Further, the use of a transformer in product designs can introduce additional UL issues.
Therefore, it is a primary object of the present invention to provide an off-line switching power supply that improves over the state of the art.
It is a further object of the present invention to provide an off-line switching power supply capable of generating negative voltages.
Yet, another object of the present invention is to provide an off-line switching power supply that is low in cost to manufacture.
A further object of the present invention is to provide an off-line switching power supply that does not require use of a transformer to generate negative voltages.
A further object of the present invention is to provide an off-line switching power supply that uses voltage feedback to regulate an output voltage.
A still further object of the present invention is to provide an off-line switching power supply that is capable of producing multiple outputs with different negative voltages.
These and other objects, features or advantages of the present invention will become apparent from the specification and claims that follow.